Method and an apparatus for making tubes

ABSTRACT

An apparatus for forming tubes from a spirally wound metallic strip wherein one longitudinal border of the strip is bent on edge and the other border is bent to form a U-shaped fold to receive the first border. The apparatus embodying a feeding device having cutting means to notch the longitudinal borders and associated therewith a guiding means for directing said strip to a plurality of rollers for compressing the longitudinal borders together.

United States Patent [191 Schwarz Sept. 17, 1974 METHOD AND AN APPARATUS FOR MAKING TUBES [76] Inventor: Walter Schwarz, 6020 Innsbruck,

- Innsbruck, Austria [22] Filed: Feb. 16, 1973 [21] Appl. No.: 333,001

[52] US. Cl. 72/50, 72/l29 [51] Int. Cl. B21c 37/12 {58] Field of Search 72/49, 50, I29

[56] References Cited UNITED STATES PATENTS 1,890,077 12/1932 Elting 72/52 3,269,162 8/1966 Fay 3,456,471 7/1969 Ellis 72/177 Primary Examiner-Charles W. Lanham Assistant Examiner-Robert M. Rogers Attorney, Agent, or Firm-Kemon, Palmer & Estabrook 7 1 ABSTRACT An apparatus for forming tubes from a spirally wound metallic strip wherein one longitudinal border of the strip is bent on edge and the other border is bent to form a U-shaped fold to receive the first border. The apparatus embodying a feeding device having cutting means to notch the longitudinal borders and associated therewith a guiding means for directing said strip to a plurality of rollers for compressing the longitudinal borders together.

12 Claims, 15 Drawing Figures PAIENTEDSEPITIBH 3.885.684

SHEEI 1 0F 7 Fig. 4 I 1' I Fig. 5

j v v K PATENTEUSEPI m SHEET 5 OF 7 Fig. 12

PATENTEUSEPIYIHM 3835.684 7 I sum 7 BF 7 I METHOD AND AN APPARATUS FOR MAKING TUBES The present invention relates to a method for making tubes from a spirally wound strip one longitudinal border of which is bent on edge and the other longitudinal border of which forms an U-shaped fold which is also bent on edge towards the same side of the strip and extends in parallel with said border, which fold, after said edge has engaged it, is closed by compression, as well as to a device for performing said method.

Several proposals have been made for forming tubes from a metallic strip whereby the fabricated tube has a helically shaped seam. With these known devices the longitudinal portions of the strip are intermeshed, compressed and bent over a mandrel to provide the desired tubular form. All the known methods have the disadvantage that for each tube diameter a specific mandrel with the desired diameter is required. This means not only that such mandrels have to be stored but also that dead phases occur in manufacturing since the replacement of mandrels takes relatively long time. Consequently, by replacing the mandrels repeatedly, the economy of production will suffer.

It is therefore the object of the present invention to form tubes from a metallic strip whereby a mandrel can be dispensed with and the beforementioned disadvantages are eliminated, thereby permitting the production of tubes of different diameters without the necessity of substantial readjustment of the device during produc tion. Three simple technical facts interacting effectually in a corresponding device are of basic interest in view of achieving this purpose:

I. It is possible without expending much energy to twist the small marginal strip bent over from a sheetmetal strip and measuring about mm through 90 over a distance of about 40 mm.

2. It is possible without any difficulty to flatten a sheet-metal tube with a diameter of about 60 mm and more over a portion of about 40 mm in order to compress the interrneshed edges of the sheet-metal strip, whereby the advancing fabricated tube restores by itself its round shape.

3. A sheet-metal strip with an edge of about 10 mm which is bent at an angle of 90 can be twisted without any difficulty, if the bent edge at some millimeters intervals is provided with cuts or if it is deformed and given a wave shape.

In applying this knowledge a method is proposed wherein the bent edge of the strip is notched or undulated, then wound in the conventional way and inserted into the U-shaped fold which fold together with the intermeshed edge is then bent through 90 and compressed.

A further advantage for forming such tubes is provided if the edge of the strip forming an U-shaped fold is also notched before being wound. It is, furthermore, particularly advantageous if the cuts are executed before the fold is formed, for instance, by applying the punching method, wherein a cut-free marginal portion is left between the adjacent outer edge of the strip and the cuts. A tube so formed, after being compressed, is provided with a particularly tight seam, since the flat edge portion closely joins the inserted side of the bent edge. Thereby a gastight seal is achieved which seal is particularly appreciated since tubes of this kind are mainly used for flues and the like.

A particularly tight seal is achieved if the length of the cuts is selected in a manner wherein after the formation of the U-shaped fold a cut-free strip is provided on the parallel side of the fold opposite the marginal portion having substantially the same breadth, which strip, after the edge has engaged the fold, is compressed with the fold to a gastight seal. For this purpose it is suitable that the outer side of the fold is drawn up to such a height that the edge of the fold flushes with the surface of the strip.

The apparatus for performing the method according to the invention comprises a pivotable strip feeding means and guiding means inserting one edge of the strip into the other folded strip, as well as concentric compression rolls which compress the intermeshed edges of the strip, said apparatus being characterized in that the pivotable strip feeding device consists of a bearing plate pivotable about a pin and secured to a base by means of a fixing device on which bearing plate is supported a cutter to notch the edge of the strip or a deforning means to undulate it, further characterized in that the guiding means consists of a guide forming a vertical slot for the fold of the strip, of a further guide arranged behind the former in the feed direction of the strip to be wound and of a grooved roll, whereby, as it is known in the art, one roll of each pair of rolls extending horizontally and in parallel is secured to the base closely above the guiding means and the grooved roll.

The further guide means may have the same shape as the grooved roll whereby the slot of the guide and the lateral borders of the groove of the guide arrangement and the roll situated at the same side are flushing vertically. Said guide may, however, consist of a pair of rolls arranged below the roll and extending vertically relative to it, whereby the rolls are spaced away from each other at a distance corresponding substantially to the breadth of the slot of the guide, the passage formed by this distance being positioned on an imaginary vertical plane passing through the slot of the guide.

The cutter preferably consists of two contrarotating wheels provided with interlocking cutter teeth between which passes the edge of the strip. It would, however, also be possible to fit only one roll with cutter teeth and to provide a tangent support plate or a counter roller instead of the second sprocket.

The deforming device preferably consists of two contra-rotating wheels intermeshing by means of rounded teeth between which the edge of the strip passes whereby it is also possible to employ only one cog wheel.

Examples of an embodiment of the present invention arehereinafter described with reference to the accompanying drawings without being limited to them.

FIG. 1 is a view of a strip provided with a fold and a bent edge.

FIGS. 2 and 3 are diagramms of such a strip whereby in FIG. 2 the bent edge is provided with cuts whereas in FIG. 3 said edge is undulated.

FIGS. 4 and 5 are front views of a strip with an undulated border bent on edge and a flanged fold wherein engages the edge.

FIG. 6 shows a section of a strip with cuts at both sides of the strip.

FIG. 7 is a vertical section of said strip with an already formed fold and a border bent on edge.

FIG. 8 is a diagram of such a construction with cuts and FIG. 9 with an undulated border bent on edge.

FIG. 10 is a section of a finished rolled tube shortly 7 after the output.

FIG. 11 is a top plan view of the apparatus according to the invention.

FIG. 12 is a section of the device along the lines XII-XII of FIG. 11.

FIG. 13 is a section along lines XIII-XIII of FIG. 11.

FIG. 14 is a section along lines XIVXIV of FIG. 11 and FIG. 15 shows a detail of the present apparatus with a varied construction of the further feeding device.

The apparatus according to the invention consists of a bearing plate 11 pivoted on a pin 12 and secured to base 20 adapted to be fixed in any desired position by means of a fixing device 14. This fixing device 14 consists of a screw bolt attached to base 20 around which a circular slot 22 of bearing plate 11 can be guided, a nut 21 permitting the fixing to the screw bolt in any desired position. Furthermore a guide 17 is provided on bearing plate 11 which guide forms a small slot extending vertically relative to the bearing plate 11. According to the embodiment under FIG. 11 a pair of rolls 9 and 10 is placed on the bearing plate 11 the axes of which are arranged vertically, the two rollers being spaced away from each other at a distance that corresponds to the breadth of the slot of the guide 17 and in continuation of the slot forms a passage. In continuation of the line passing through the slot and the passage is situated groove 19 of the roll 18 arranged on bearing plate 11.

On base 20 two rolls 7 and 8 are provided extending in parallel and spaced away from each other, roll 7 being arranged closely above pairs of rolls 9 and 10 and roll 8 closely above roll 18. These rolls 7 and 8 may be driven by any power supply.

On a protruding portion of bearing plate 11 a cutter 4 is provided consisting according to the embodiment under FIG. 11 of two contrarotating wheels with intermeshing cutter teeth, rotating around vertically extending axes, whereby a plane extending vertically relative to the connecting line of the two axes and passing between the wheels is spaced from a similar imaginary plane passing through guide 17 at a distance that corresponds to the breadth of strip 1 to be machined.

In order to apply the method according to the invention use will be made of the above-described apparatus as follows:

The sheet-metal strip prefabricated in the known manner (FIGS. l) on one of its longitudinal edges is provided with a fold 2 forming an U-shaped flange projecting from the body of the strip at a right angle, the other longitudinal edge forming a single edge 3 bent at a right angle towards the same side. Both edges measure about mm in height.

The sheet-metal strip so prefabricated is provided with a butt edge 5 diagonally cut relative to the strip run the length of which corresponds to the circumference of the tube 6 to be machined. After inserting edge 3 of strip 1 into cutter 4 effecting cuts at 3 mm intervals the forward end of butt edge 5 is passed by hand through pair of rolls 7 and 8, then flexed around it and guided backward toward the slot of guide 17 into which end 15 is then inserted. This flexing operation can easily be performed because of the provision of cuts in edge 3.

Before starting the flexing operation bearing plate 11 is turned round pin 12 and fixed by the fixing device in such a position that butt edge 5 before being flexed back around rolls 7 and 8 extends vertically relative to their axes as well as to axis 13 of tube 6 to be formed.

In the meantime, fold 2 of sheet metal strip 1 which has advanced in the above described manner has also arrived at the feeding device 17 such that the forward end 15 when being fed to device 17 simultaneously engages fold 2. In passing through passage 16 between rolls 9 and 10 and under roll 7 the intermeshed flanges butt against groove 19 of roll 18 where they are twisted through by hand, for instance, by means of tongs, and then inserted into the groove.

When metal-sheet strip 1 fed to the device in the described manner is then forwarded by rolls 7 and 8 driven by an engine, the flanges will automatically be joined together and twisted through 90, whereby roll 8 arranged above roll 18 will lock together fold 2 and the engaging edge 3.

Instead of cutter 4 notching strip 1 of FIG. 1 as can be seen in FIG. 2, a deforming device may be employed undulating flange 3 as under FIG. 3, whereby said flange on its free end is more heavily undulated than than on its edge adjacent to the body of the strip.

Between guide 17 and recess 19 of roll 18 the body of the strip of tube 6 being formed is flattened to ensure that the fold formed by the intermeshed flanges is tightly compressed. During the further advancing process the tube will become round by itself and show a circular section.

As shown in FIG. 15 rolls 9 and 10 may also be replaced by a roll 18' having the same form as roll 18 of the compression means. In using this construction the structure of the device according to the invention could even be simplified.

FIGS. 6 to 9 show a strip 1 which on its side adapted to form fold 2 is provided with cuts 23, effected, for instance, by applying the punching method and arranged at some millimeters intervals. The length and the position of cuts 23 is selected in such a manner that, after the formation of fold 2 cut-free marginal portions 24 and 25 are left at the upper ends of its parallel running sides which portions correspond and are opposed to each other. This form of the strip to be wound is particularly suitable since it permits easier winding of the folded edge.

Edge 3 on the other side of the strip may also be provided with cuts 26 (FIG. 8) or undulation 27 (FIG. 9) the length of which is selected in a manner wherein with the bent edge 3 engaging fold 2 a flat strip 28 free of cuts and undulations is placed between marginal portions 24 and 25, whereby strips 24, 25 and 28 when being pressed provide a gastight seal so that in the event of gas seeping through cuts 23 and 26 an evaporation will be prevented.

If marginal portions 24 and 25 have no cuts, edge 3 can be inserted into fold 2 more easily than in case of cuts which cuts 23 extend until edge 29 and form tongues which as a result of maching are not always coplanar so that they may strut with the edge 3 when being inserted.

Various constructions, as the modified embodiments hereinbefore described, are possible within the scope of the invention and it will be appreciated that all such variations with the object to eliminate a mandrel and to deform or notch the edge to be inserted into the fold of the other edge may be embodied within the scope of the appended claims.

What I claim is:

1. Method of producing tubes from a spirally wound strip one border of which is bent on edge and the other border of which forms an U-shaped fold which is also bent on edge towards the same side of the strip and extends in parallel with the before-mentioned edge, said edges having a planar surface, said fold of the second edge receiving the first mentioned edge prior to being closed by compression, characterized in that the planar surface of said bent edge of said strip is interrupted prior to being wound in the conventional way and inserted into the U-shaped fold which fold together with the engaging edge is then bent through 90 and compressed along a straight line in the running direction of the strip.

2. Method according to claim 1 whereby the edge of the strip forming the U-shaped fold is also provided with cuts before the winding operation.

3. Method as claimed in claim 2 whereby the cuts in the U-shaped fold are executed before its formation, for instance, by means of the punching method, whereby a cut-free margin is left between the adjacent outer edge of the strip and the cuts.

4. Method as claimed in claim 2 whereby the length of the cuts is selected in a manner wherein after the for mation of the U-shaped fold a cut-free strip is provided on the parallel side of the fold opposite the flange having substantially the same breadth which strip after the bent edge has engaged the fold is compressed with the fold to a gastight seal.

5. Method as claimed in claim 3, wherein the outer side of the fold is drawn up to such a height that its edge is flush with the surface of the strip.

6. Method according to claim 1 wherein the bent edge of said strip is formed with a plurality of spaced slits.

7. Method according to claim 1 wherein the bent edge of said strip is formed with an undulating surface.

8. Apparatus for producing tubes from a spirally wound strip consisting of a strip having opposite borders bent on edge and extending in parallel planes from said strip with one edge forming a U-shaped fold, said bent edges having planar surfaces, a base member, a pivotable strip feeding device and a guiding means supported on said base, said pivotable strip feeding device consisting of a bearing plate pivotable about a pin carried by said base, said bearing plate having a member supported thereon for engaging and interrupting the planar surface of at least one edge of said strip, said guiding means consisting of a guide forming a vertical slot for the U-shaped fold of said strip, a further guide consisting of a grooved roll arranged on said bearing plate and positioned behind the first mentioned guide in the feed direction of said strip to be wound, compression rolls carried by said base and arranged in spaced parallel relation to one another, said compression rolls being positioned above said guiding means and said grooved roll for compressing the edges of said strip subsequent to the inserting of the one edge of said strip into the U-shaped folded edge.

9. Apparatus as claimed in claim 8 wherein the further guide means has the same shape as the grooved roll whereby the slot of the guide and the lateral borders of the grooves of the guide means and the roll are coplanar.

10. Apparatus as claimed in claim 8 wherein the further guide means consists of a pair of rolls arranged below the roll and extending vertically relative to it, whereby the rolls are spaced away from each other at a distance corresponding substantially to the breadth of the slot of the guide, the passage formed by this distance being positioned on the imaginery vertical line passing through the slot of the guide.

11. Apparatus as claimed in claim 8 wherein the cutter consists of two contrarotating wheels provided with intermeshing cutter teeth between which passes the bent edge of the strip.

12. Apparatus as claimed in claim 8 wherein the deforming device consists of two contrarotating wheels intermeshing with rounded teeth between which the bent edge of the strip passes.

STATES PATENT OFFICE v CERTIFICATE OF CORRECTION Patent No. 3,835,684 D d September 17, 1974 Inventor (W Wal ter Schwarz the above-identified patent It is certified that error appears in v rrected as shown below:

and that said Letters Patentare hereby co [30] Foreign Applicatiofi Priority Data Au Stria..-.......----

February 7, 1973 Austria...........

Signed and sealed this 17th day of Deeember 1974.

(SEAL) Attest:

c. MARSHALL DANN HcCOY M. GIBSON JR.

Commissioner of Patents Attesting Officer FORM PC4050 (1069 USCOMM-DC 00S76-P69 i e 0.5. covrnmmn' rmunncorr'lcz an o-su-su. 

1. Method of producing tubes from a spirally wound strip one border of which is bent on edge and the other border of which forms an U-shaped fold which is also bent on edge towards the same side of the strip and extends in parallel with the beforementioned edge, said edges having a planar surface, said fold of the second edge receiving the first mentioned edge prior to being closed by compression, characterized in that the planar surface of said bent edge of said strip is interrupted prior to being wound in the conventional way and inserted into the U-shaped fold which fold together with the engaging edge is then bent through 90* and compressed along a straight line in the running direction of the strip.
 2. Method according to claim 1 whereby the edge of the strip forming the U-shaped fold is also provided with cuts before the winding operation.
 3. Method as claimed in claim 2 whereby the cuts in the U-shaped fold are executed before its formation, for instance, by means of the punching method, whereby a cut-free margin is left between the adjacent outer edge of the strip and the cuts.
 4. Method as claimed in claim 2 whereby the length of the cuts is selected in a manner wherein after the formation of the U-shaped fold a cut-free strip is provided on the parallel side of the fold opposite the flange having substantially the same breadth which strip after the bent edge has engaged the fold is compressed with the fold to a gastight seal.
 5. Method as claimed in claim 3, wherein the outEr side of the fold is drawn up to such a height that its edge is flush with the surface of the strip.
 6. Method according to claim 1 wherein the bent edge of said strip is formed with a plurality of spaced slits.
 7. Method according to claim 1 wherein the bent edge of said strip is formed with an undulating surface.
 8. Apparatus for producing tubes from a spirally wound strip consisting of a strip having opposite borders bent on edge and extending in parallel planes from said strip with one edge forming a U-shaped fold, said bent edges having planar surfaces, a base member, a pivotable strip feeding device and a guiding means supported on said base, said pivotable strip feeding device consisting of a bearing plate pivotable about a pin carried by said base, said bearing plate having a member supported thereon for engaging and interrupting the planar surface of at least one edge of said strip, said guiding means consisting of a guide forming a vertical slot for the U-shaped fold of said strip, a further guide consisting of a grooved roll arranged on said bearing plate and positioned behind the first mentioned guide in the feed direction of said strip to be wound, compression rolls carried by said base and arranged in spaced parallel relation to one another, said compression rolls being positioned above said guiding means and said grooved roll for compressing the edges of said strip subsequent to the inserting of the one edge of said strip into the U-shaped folded edge.
 9. Apparatus as claimed in claim 8 wherein the further guide means has the same shape as the grooved roll whereby the slot of the guide and the lateral borders of the grooves of the guide means and the roll are coplanar.
 10. Apparatus as claimed in claim 8 wherein the further guide means consists of a pair of rolls arranged below the roll and extending vertically relative to it, whereby the rolls are spaced away from each other at a distance corresponding substantially to the breadth of the slot of the guide, the passage formed by this distance being positioned on the imaginery vertical line passing through the slot of the guide.
 11. Apparatus as claimed in claim 8 wherein the cutter consists of two contrarotating wheels provided with intermeshing cutter teeth between which passes the bent edge of the strip.
 12. Apparatus as claimed in claim 8 wherein the deforming device consists of two contrarotating wheels intermeshing with rounded teeth between which the bent edge of the strip passes. 